POLYADDITION PRODUCTS WHICH CONTAIN URETDIONE GROUPS

PRODUITS DE POLYADDITION CONTENANT DES GROUPEMENTS D'URETDIONE

English Abstract

Abstract of the Disclosure
The present invention teaches a novel polyisocyanate
lacquer binder and a method of preparing it. The binder is
prepared by reacting uretdione containing polyisocyanates
optionally mixed with uretdione fee diisocyanates with water
or with low molecular weight compounds which have two alco-
holic hydroxyl groups per molecule. Optionally these com-
pounds may be mixed with up to 60 wt.% based on the total
weight of hydroxyl bearing compounds, of low molecular
weight compounds with one active alcoholic hydroxyl
group per molecule. The proportion of
reactants is so selected that the binder produced has from 5
to 20 wt.% of latent isocyanate groups in the form of unopened
uretdione rings. The binder can then be mixed with poly-
hydroxyl compounds having molecular weights of 400 to 10,000
and conventional lacquer pigments and fillers. This mixture
can then be coated on a substrate and the coating heated
to above 100°C to effect hardening.

Claims

The embodiments of the invention in which exclusive
property or privilege is claimed are defined as follows:
1. Process for the preparation of pulverulent
polyaddition products which contain uretdione groups and which
are suitable for use as cross-linking agents for powder lacquer
binders or powder lacquer binder components which contain
active hydrogen atoms, by reacting polyisocyanates which contain
a uretdione group or mixtures of such polyisocyanates and di-
isocyanates which are free from uretdione groups with water or
with compounds which contain alcoholic hydroxyl groups capable
of reacting with isocyanate groups, characterized in that:
a) the reactants are reacted together at an
NCO/active hydrogen ratio of between 1:1 and 1:1.6;
b) the compounds containing alcoholic hydroxyl
groups which are reactive with isocyanate groups
are aliphatic, cycloaliphatic or araliphatic
compounds with molecular weights of from 62 to 300
which contain a total of two hydroxyl groups,
mixed with from 0 to 60% by weight, based on the
total quantity of compounds which are water and
compounds which contain alcoholic hydroxyl groups,
of aliphatic, cycloaliphatic or araliphatic
compounds with molecular weight of from 32 to
300 which contain one hydroxyl group; and
c) the reactants are used in such proportions that
the products of the process contain from 5 to 20%
by weight of latent NCO groups and from 0 to 2
hydroxyl end groups.
31

2. Process according to Claim 1, characterized
in that the compounds with active hydrogen atoms used
correspond to the formula:
R(OH)n
wherein n = 1 or 2 and if n = 1, R denotes an aliphatic hydro-
carbon group with from 1 to 18 carbon atoms optionally interrupted
by ether oxygen atoms or a cycloaliphatic hydrocarbon group
with from 5 to 7 carbon atoms and, if n = 2, R denotes an
aliphatic hydrocarbon group with from 2 to 18 carbon atoms
optionally interrupted by ether oxygen atoms or a cycloali-
phatic hydrocarbon group with from 5 to 15 carbon atoms.
3. Polyaddition products with uretdione groups
obtainable according to Claim 1 having a melting point between
30° and 240°C.
4. The process of Claim 2, wherein the polyisocyanates
which contain uretdione groups are dimerized diisocyanato-
toluene.
5. A process for coating a substrate by:
a) mixing the cross-linking agents of Claim 3
having a melting point between 30 and 240°C
with from 5 to 85% by weight based on the
total quantity of binder, of polyhydroxyl
compounds free from uretdione groups having
molecular weights of from 400 to 10,000
and conventional lacquer pigments and fillers,
b) coating the mixture on a substrate, and
c) heating the coating at temperatures in
excess of 110°C until it hardens.
32

6. The process of Claim 1, wherein 0 to 10 wt. %
of the monofunctional active hydrogen compounds are used
and the reaction is carried out at a temperature of about 0
to 150°C.
7. The process of Claim 6, wherein the reaction
is carried out at a temperature of about 80 to 120°C.
8. The product of Claim 1, having a melting point
in the range of about 30 to 240°C and a molecular weight of
800 to 5000.
9. The product of Claim 8, having a melting point
in the range of 70 to 180°C and a molecular weight of 900
to 4000.
10. The process of Claim 5, wherein the polyhydroxyl
compound has a softening point of between 60 and 120°C.
11. The process of Claim 10, wherein the polyhydroxyl
compound has a softening point of between 80 and 100°C.
12. The process of Claim 5, wherein the mixture
has a softening point of between 50 and 150°C and wherein
the mixture begins to cross-link at temperatures at least
10°C in excess of the softening point.
33

13. A powder lacquer which may be hardened at tem-
peratures above 110°C comprising:
1) the polyaddition product with uretdione groups
of Claim 3;
2) 5 to 85 wt. % based on the weight of 1 and 2
of polyhydroxyl compounds free from uretdione
groups having molecular weights of from 400 to
10,000; and
3) conventional lacquer pigments and fillers.
14. A process for the preparation of pulverizable
latent cross-linking agents which comprises:
1) dimerizing diisocyanates in the presence
of a dimerization catalyst,
2) then inactivating the dimerization catalyst,
and
3) reacting said dimerized reaction mixture
containing said inactivated catalyst with
4) compounds containing hydrogen atoms reactive
with isocyanate groups selected from the
group consisting of water and aliphatic
cycloaliphatic or araliphatic compounds with
molecular weights of 62 to 300 which con-
tain one or two hydroxyl groups wherein said
compounds are comprised of no more than 60
wt. % of monohydroxy compounds,
5) wherein the reactants are used in such pro-
portions that the NCO/OH ratio is between
1:1 and 1:1.6 and the products of the pro-
cess contain from 5 to 20 wt. % of latent
NCO groups and from 0 to 2 hydroxyl end
groups.
34

15. The process of claim 14, wherein the entire process is
conducted in a single vessel.
16. The process of claim 14, wherein the dimerization
catalyst is selected from the group consisting of tertiary
phosphines which carry at least one aliphatic substituent and
pyridine.
17. The process of claim 16, wherein the dimerization
catalyst is inactivated by the addition of sulphur.
18. The process of claim 14, wherein the dimerization
catalyst is selected from the group consisting of triethyl-
phosphine, tributyl phosphine, phenyldimethylphosphine and
pyridine and 0.1 to 5 wt. % of catalyst based on the weight of
diisocyanate is used.
19. The product obtainable by the process of claim 14,
containing inactivated dimerization catalyst and having a
melting point in the range of about 30 to 240°C. and a
molecular weight of 800 to 5000.
20. A process for coating a substrate by:
a) mixing the cross-linking agents of claim 19,
having melting points of 30° to 240°C with
from 5 to 85 wt. %, based on the total
quantity of a lacquer binder, of poly-
hydroxyl compounds free from uretdione
groups having molecular weights of from
400 to 10,000 and conventional lacquer
pigments and fillers,
b) coating said mixture on a substrate, and
c) heating the coating at temperatures in
excess of 110°C until it hardens.

Description

o ~ ~ r Mo-1501-P
v ~Y~ ~ LeA 15,476
'- ~
POLYADDITION PRODUCTS WHICH CONTAIN
URETDIONE GROUPS
.. . ~
Field of the Invention
This invention relates to a process for the pre-
paration of new pulverulent polyaddition products which
contain uretdione groups and which are suitable for use as
cross-linking agents for powder lacquers based on binders or
binder components which contain active hydrogen atoms, compounds
obtainable by this process and their use as binder components
10 in powder lacquers.
Background of the Invention
Polyurethanes which contain uretdione groups in
the macromolecule are already known (Kunststoff Handbuch
Volume VII, Polyurethane, published by Vieweg-Hochtlen, Carl- -
15 Hanser-Verlag Munich, 1966, pages 17, 37). It is also known
that compounds which contain uretdione groups undergo opening -
of the uretdione ring at elevated temperatures to liberate
the isocyanate groups (J.~. Saunders and K.C. Frisch "Poly-
urethanes, Chemistry and Technology", Part I, Interscience
20 Publishers (1962) pages 113 et seq.).
The coating of metal articles with pulverulent
; coatings is also already known. Various polymers which are
applied as powders to the metal article and form a protective
layer on it when melted may be used as one-component systems
25 which are either self cross-linking or cannot be cross-linked.
Two-component or multicomponent systems and their
use as lacquer raw materials, e.g. mixtures of blocked
polyisocyanates with polyesters which contain hydroxyl groups,
etc. are also known in the art (German Patent Specification
q~ ~,,.
LeA 15,476 -¦'

No. 946,143). These compounds have the advantage over products
which contain free isocyanate groups that at low temperatures,
e.g. room temperature, they remain practically unchanged even
when stored for a considerable length of time in the presence
of water and polyalcohols and only liberate the blocking ~ -~
agents at elevated temperatures, generally substantially above
100C, and then react with the polyfunctional reactants
available, e.g. polyols, to form a cross-linked coating film.
These blocked isocyanates have the disadvantage that
the blocking agent is liberated during the hardening reaction
and given off to the surroundings. Some of the blocking agents
are not physiologically harmless (phenols, mercaptans) and
also have the added disadvantage of forming deposits in the
cooler parts of a large stoving apparatus and therefore requir- -
ing substantial cleaning operations.
The polyaddition products with uretdione groups
described in United States Patent No. 3,248,370 and German
Offenlegungsscnriften Nos. 20 44 833 and 22 21 170 are also
unsuitable for use as binders or binder components for thermo-
setting powder lacquers since they do not fulfill all the
following basic requirements simultaneously:
a) the ability to be reduced to powders
at temperatures below 30C
b) softening or melting point between 30 I-
and 240C preferably 70 to 180C; and
c) (in combination with reactants which
contain active hydrogen atoms) a hard- -
ening temperature at least 10 to 40C
above the softening or melting point (of
the combination) and preferably above
LeA 15,476 _~-

108~1~6
110C, in particular between 140 and 220C.
This invention points the way to new polyisocyanate
polyaddition products which contain uretdione groups and
which satisfy these conditions and are therefore valuable
new binder components for thermosetting powder lacquers.
Summary of the Invention
This invention relates to a process for the pre-
paration of pulverulent polyaddition products which contain
uretdione groups and which are suitable for use as cross-
linking agents for powder lacquer binders or binder componentswhich contain active hydrogen atoms, by reacting polyisocya-
nates which contain a uretdione group or mixtures of such poly-
isocyanates and diisocyanates which are free from uretdione
groups with water or with compounds which contain alcoholic
hydroxyl groups capable of reacting with isocyanate groups,
characterized in that:
a) the reactants are reacted at an NCO/active
hydrogen ratio of between 1:1 and 1:1.6;
b) the compounds which contain alcoholic hydroxyl
groups capable of reacting with isocyanate
groups are aliphatic, cycloaliphatic or arali-
phatic compounds with molecular weights of from
. 62 to 300 which contain a total of two hydroxyl
:l groups, mixed with from 0 to 60~ by weight,
based on the total quantity of compounds which
contain alcoholic hydroxyl groups and compounds
which are water, of aliphatic, cycloaliphatic
or araliphatic compounds within a molecular
weight range of from 32 to 300 which contain
one hydroxyl group; and
-3-
~2 LeA 15,476

1~84~
c) the proportions by weight of reactants
are so chosen that the products of the
process contain from 2 to 20% by weight
; of latent NCO groups and from 0 to 2
hydroxyl end-groups per macromole-
cule.
This invention also relates to the new compounds
obtainable by this process.
Also, the invention relates to the use of the new
compounds obtainable by this process as binder components in
powder lacquers which may be hardened at temperatures above
110C in combination with from 5 to 85% by weight, based on
~ the total quantity of binder, of polyhydroxyl compounds with
; molecular weights of from 400 to 10,000.
By "latent NCO groups" are meant in the context
of this invention any NCO groups which are formed by thermal
decomposition of the uretdione groups and which cannot find
any reaction partners in the form of end groups of the cross-
linking agent capable of reacting with NCO groups and are there-
~ore a~ailable for the cross-linking reaction. ;
Detailed Description of the Invention
Starting materials for the process according to ~ -~
the invention are polyisocyanates which contain uretdione
groups, in particular diisocyanates of the type which may be
obtained in known manner by dimerization of organic diiso-
cyanates (see e.g. German Offenlegungsschriften Nos. 1,670,720
and 1,934,763 or "Kunststoff-Handbuch", Volume VII, Polyurethane,
Carl-Hanser-Verlag, Munich tl966), pages 16-17, and Polyurethanes:
Chemistry and Technology, Part I, Saunders-Frisch, pages 91-94).
These uretdione diisocyanates may easily be obtained from the
LeA 15,476 -4-

~8419~
corresponding isocyanates by a catalytic reaction. The catalysts
used for this purpose are preferably tertiary phosphines
which carry at least one aliphatic substituent, e.g. triethyl-
phosphine, tributylphosphine or phenyldimethyl phosphine,
or also pyridine. ~;
Dimerization may be carried out in the absence of
solvent or, preferably, in an inert organic solvent. The
preferred solvents are benzene, toluene, methyl and ethyl
qlycol acetate, dimethylformamide, xylene and other aromatic
or aliphatic hydrocarbons, also ketones, such as acetone,
methyl butyl ketone or methyl isobutyl ketone and cyclohexanone, `
and chlorinated aromatic hydrocarbons as well as any mixture
of these and other inert organic solvents.
To carry out the dimerization process, it is
essential to stop the reaction when the mixture has a certain
isocyanate con~ent, preferably when from 25 to 50% and in
particular from 26 to 39% of the NCO groups have undergone
dimerization.
The reaction temperature required varies according
to the catalyst used. For tertiary aliphatic or mixed aliphatic
aromatic phosphines the optimum temperature range is from 0 ;~
to 120C and temperatures of from 0 to 60C are preferably
employed. As is well known, if higher temperatures and lower
catalyst concentrations are employed, isocyanurates and
increasing quantitles of other by-products, such as carbo-
diimides and uretone imines, are formed. Since the dimerization
reaction in the presence of catalysts is an equilibrium reaction
and the maximum degree of dimerization is obtained at low
temperatures, it is customary to employ relatively low
3~ temperatures.
LeA 15,476 -5-

1~84196 `
~.,
For dimerization by heating in the absence of a
catalyst, temperatures of between 120 and 150C are most ;~
..
suitable. At lower temperatures, the reaction mixture takes
too long to reach equilibrium whereas at higher temperatures
substantial conversion of uretdione to isocyanurate takes
place.
The quantity of catalyst required varies according
to the nature and purity of the isocyanate and the temperature
employed. Quantities of from 0.1 to 5~ by weight, based on
the quantity of diisocyanate, are generally sufficient when
tertiary aliphatic phosphines are used. The quantities ~ ~
employed are preferably from 0.3 to 2%. ; ~-
The quantity of free NCO groups established after
a reaction time of from 0.5 to 4 hours at a reaction temperature
. . .
of from 0 to 25C in the presence of the above-mentioned
catalyst generally corresponds to a conversion of from 26 to
! 39~ of the isocyanate groups present when aromatic diisocyanates
are used. The aromatic or mixed aromatic-aliphatic uretdione
diisocyanates crystallize from the reaction mixture in the
course of dimerization. The dimerization catalyst is inacti-
vated by the addition of a heated 10% solution of sulphur in
toluene.
,
In the process according to the invention, the
uretdione diisocyanates obtainable in this way may be used
either as the sole isocyanate component or as a mixture with
diisocyanates which are free from uretdione groups. It is
particularly preferred to use mixtures of from 50 to 100% by
weight of uretdione diisocyanate and from 0 to 50% by weight
of uretdione-free diisocyanate for the process according to
the invention. Addition of the diisocyanate which is free
LeA 15,476 -6-
,.~ ,, '' ~

1~84196
from uretdione groups provides a simple means of varying the
properties of the products as desired, in particular their
melting points (see e.gO Example 1) since the monomericdiiso-
cyanate which iS free from uretdione groups is built into the
products of the process thus decreasing the melting point.
The above-mentioned diisocyanate mixture prepared
in situ and obtainable by partial dimerization of a suitable
diisocyanate is particularly suitable for use as the isocyanate
component in the process according to the invention. When
this isocyanate component is subsequently reacted with the
other reactants, the monomeric diisocyanate still present
in the reaction mixture functions as "interference component".
The reaction mixture is heated to 90 to 100C after
inacti~ation of the catalyst. A clear solution of the uretdione-
diisocyanate/diisocyanate mixture is thereby obtained. Thefree NCO group content and the latent NCO group content
in the uretdione undergo no ~urther change in this temperature
treatment. The Zerewitinoff active compounds used to
synthesize the polyuretdione-polyurethanes are then added to
the reaction mixture. The reactants may either be poured in
all at once or gradually introduced into the polyisocyanate
mixture which contains uretdione groups.
The following are examples of uretdione-free
diisocyanates which may be used in the preparation of the uret-
dione diisocyanates and as a melting point decreasing component:~liphatic, cycloaliphatic, araliphatic, aromatic
diisocyanates, such as those described e.g. by W.
Siefken in Justus Liebigs Annalen der Chemie, 562, pages
75-136, for example ethylene diisocyanate, tetramethylene-
1,4-diisocyanate; hexamethylene-1,6-diisocyanate, dodecane-
1,12-diisocyanate, cyclobutane-1,3-diisocyanate,cyclohexane-
LeA 15,476 -7-

1~84196
1,3- and 1,4-diisocyanate and mixtures of these isomers, 1-
isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane
(U.S. No.3,401,190) hexahydrotolylene-2,4- and -~,6-diisocyanate
and mixtures of these isomers, hexahydrophenylene-1,3- and/or
-1,4-diisocyanate, perhydrodiphenylmethane-2,4'- and/or -4,4'-
dlisocyanate, phenylene-1,3- and -1,4-diisocyanate, tolylene- -
2,4- and -%,6-diisocyanate and mixtures of these isomers,
diphenylmethane-2,4'- and/or 4,4'-diisocyanate and naphthylene-
1,5-diisocyanate.
Commercially readily available diisocyanates are
particularly preferred, e.g. tolylene-2,4- and -2,6-diisocyanate
and mixtures of these isomers, l-isocyanato-3,3,5-trimethyl-
5-isocyanatomethyl-cyclohexane, hexahydrotolylene-2,4- and
-3,6-diisocyanate and mixtures of these isomers, perhydro-
diphenylmethane-2,4'- and/or 4,4'-diisocyanate and hexa-
methylene-1,6-diisocyanate. ; r
; In the process according to the invention, the
isocyanate compone~t exemplified above is reacted with suitable
; compounds which contain active hydrogen atoms at an NCO/active
; 20 hydrogen ratio of between 1:1 and 1:1.6, preferably between
1:1 and 1:1.2.
These compounds with reactive hydrogen atoms are
water or aliphatic, cycloaliphatic or araliphatic ~ompaunds
with molecular weights in the range of from 62 to 300 which
contain a total of two hydroxyl groups, mixed with from 0
.. . . ... . . .. _ . . . .... . . . . .
to 60% by weight, preferably 0 to 10% by weight of aliphatic, ~
.. . . .
cycloaliphatic or araliphatic alcohols having molecular
..... . . .. . .
weights in the range of from 32 to 300, which alcohols
.. . . .
are monofunctional for the purpose of the isocyanate poly-
addition reaction.
- - - --
LeA 15,476 -B-

10841~
The reactants for the isocyanate component used in
the process according to the invention are preferably water
and/or alcohols of the formula R(OH)n wherein n = l or 2 and,
- if n = l, R denotes an aliphatic hydrocarbon group with
S from 1 to 18 carbon atoms optionally interrupted by eth~r oxygen
atoms or a cycloaliphatic hydrocarbon groups with from 5 to 7 car-
bon atoms or a benzyl radical and, if n = 2, R denotes an aliphatic
hydrocarbon group with from 2 to 18 carbon atoms optionally inter-
rupted by ether oxygen atoms or a cycloaliphatic hydrocarbon group
0 with from 5 to 15 carbon atoms or an araliphatic hydrocarbon group
with 8 - 14 carbon atoms which may contain ether groups~
, ~
The following are examples of such dihydric alcohols:
ethylene glycol, propylene-l,2- and -l,3-glycol, butylene-l,4-
and -2,3-glycol~ hexane-l,6-diol, octane-l,8-diol, neopentyl
glycol, l,4-bis-hydroxymethylcyclohexane, 2-methyl-propane-
, ~
1,3-diol, diethyleneglycol, triethyleneglycol, tetraethylene-glycol,
dipropyleneglycol, tripropyleneglycol and dibutylene-glycol, 1,4-
dihydroxy-cyclohexane, 1,4-bis-(2-hydroxyethoxy)-benzene. 2-ethyl-
hexane-1,3-diol is particularly preferred as a diol which acts as -~
0 linking component in the synthesis of the polyuretdione polyurethanes
according to the invention.
Examples of suitable monohydric alcohols include
methanol, ethanol, n-butanol, n-decanol, n-octadecanol, cyclo-
hexanol, benzyl alcohol, glycol monoethylether and the ethoxy-
lation and/or propoxylation products of monohydric alcohols
within the above-mentioned molecular weight range.
The quantity in which the compounds which are mono-
functional for the purpose of the isocyanate polyaddition
reaction should be used in the process according to the
invention depends particularly on the functionality of the
uretdione polyisocyanate used. Particularly if partial
dimerization o~ aromatic diisocyanate i3 carried out and
particularly of tolylene diisocyanates, the reaction products
LeA 15,476 -9-

~084196
consists practically exclusively of mixtures of strictly
difunctional isocyanates. When aliphatic diisocyanates are
dimerized, however, the possibility of the isocyanate mixture
also containing higher functional polyisocyanates and in
particular polyisocyanates which contain isocyanurate groups
cannot be completely excluded. The presence of these higher
functional components must be compensated or overcompensated
in the process according to the invention by adding mono-
functional reactants. In the process according to the invention
the reactants are otherwise used in such proportions that the
products of the process contain from 4 to 20% by weight,
preferably from 5 to 15% by weight, of latent isocyanate groups
and from 0 to 2 hydroxyl end groups per molecule.
The properties of the products and particularly
their melting points may easily be influenced by suitable
choice of the reactants which contain active hydrogen atoms.
Diols with branched hydrocarbon chains generally give rise
to lower melting products than those obtained from diols
with straight carbon chains.
To carry out the process according to the invention,
the reactants are mixed in the given proportions. Generally,
the isocyanatecomponent is introduced into the reaction vessel
and the other reactant is added. The reaction may be carried
out in the absence of solvent or in the presence of suitable
solvents, e.g. benzene, toluene, methyl, or ethyl glycol
acetate, dimethylformamide, xylene or other aromatic or
aliphatic hydrocarbons, also ketones, ~uch as acetone, methyl
butyl ketone or methyl isobutylketone and cyclohexanone and
chlorinated aromatic hydrocarbons as well as any mixtures
of these and other inert organic solvents.
LeA 15,476 -10-

1084196
The process according to the invention is generally
- carried out at temperatures of from 0 to 150C preferably
from 80 to 120C. The products of the process generally
crystallize during and after cooling of the reaction mixture.
Catalysts which accelerate the isocyanate polyaddition reaction
may also be used in the process according to the invention.
Only catalysts which do not contain strongly basic centers may ;
be used because those with strongly basic centers, which are
otherwise commonly used in polyisocyanate chemistry, are liable
to cause premature opening of the uretdione ring in the process
according to the invention.
On the other hand, organic metal compounds may be
used as catalysts in the process according to the invention,
particularly organic tin compounds.
The organic tin compounds used are preferably tin-(II)
salts of carboxylic acids, such as tin-(II) acetate, tin-(II)
octoate, tin-(II) ethyl hexoate and tin-(II) laurate, and the
dialkyl tin salts of carboxylic acids, e.g. dibutyl tin
diacetate, dibutyl tin dilaurate, dibutyl tin maleate or
dioctyl tin diacetate.
Other examples of catalysts which may be used
in the process according to the invention and details
concerning the action of these catalysts have been described
in Kunststoff-Handbuch, Volume VII, published by Vieweg and
Hochtlen, Carl-Hanser-Verlag, Munich (1966) e.g. on pages
96-102 and Polyurethanes: Chemistry and Technology, Volume I,
Chemistry, Saunders and Frisch, pages 127-215.
The catalysts are generally used in a quantity
of between about 0.001 and 10% by weight based on the quantity
of compounds containing hydrogen atoms which are reactive with
isocyanates.
LeA 15,476 -11-

1~84196
.. .
Reaction retarders may also be used in the process
according to the invention, e.g. substances which are acid
in reaction, such as hydrochloric acid or organic acid
halides.
The reaction mixtures are generally worked-up by
first freeing the polyuretdione polyurethanes from any solvent
used. This may be carried out by simply drying the crystalline
polyuretdione polyurethane in air or by other known methods,
such as spray drying or melt extrusion in the evaporating
screw.
The products according to the invention are generally
compounds with molecular weights of from 800 to 5000 preferably
from 900 to 4000. They have a melting point of from 30 to 240C
preferably from 70 to 180C. They are particularly suitable
for use as hardeners for higher functional thermoplastic
compounds which contain Zerewitinoff active hydrogen atoms.
In combination with such compounds which contain Zerewitinoff
active hydrogen atoms the products of the process form systems
which may be hardened at temperatures of above 110C,
preferably from 160 to 220C to form high quality synthetic
resins. The most important field of application for such
systems is their use as binders for powder lacquers.
Suitable reactants for the products of the
process for producing such thermosetting systems are compounds
of the kind known per sè in polyurethane chemistry which
contain amino, thiol, carboxyl and/or hydroxyl groups. It
is preferred to use polyhydroxyl compounds, in particular
compounds with from 2 to 8 hydroxyl groups and especially
those with a molecular weight of from 400 to 10,000 preferably
from 1000 to 6000, e.g. polyesters, polyethers, polythioethers,
polyacetals, polycarbonates, polyesteramides, polyepoxides and
LeA 15,476 -12-

1~841g6
polyacrylates which contain at least 2, generally 2 to 8
and preferably 2 to 4 hydroxyl groups, of the kind which are
; known ~er se for producing polyurethanes.
Suitable polyesters with hydroxyl groups include,
e.g. the reaction products of polyhydric alcohols, preferably
dihydric alcohols, with the optional addition of trihydric
alcohols, and polybasic, preferably dibasic, carboxylic acids.
Instead of the free polycarboxylic acid, the corresponding
polycarboxylic acid anhydrides or esters with lower alcohols
or mixtures thereof may be used for producing the polyesters.
The po.ycarboxylic acids may be aliphatic, cycloaliphatic, ~-
aromatic and/~or heterocyclic and may be substituted, e.g. by
halogen atoms, and/or may be unsaturated. The following
are mentioned as examples: succinic acid, adipic acid, suberic
acid, azelaic acid, sebacic acid, phthalic acid, isophthalic
acid, trimellitic acid, phthalic acid anhydride, tetrahydro-
phthalic acid anhydride, hexahydrophthalic acid anhydride,
. .
tetrachlorophthalic acid anhydride, endomethylene tetrahydro-
phthalic acid anhydride, glutaric acid anhydride;maleic acid,
maleic acid anhydride, fumaric acid, dimeric and trimeric
fatty acids, such as oleic acid, optionally mixed with monomeric
fatty acids, dimethylterephthalate, and bis-glycol terephthalate.
Furane-2,5-dicarboxylic acid may also be used.
Suitable polyhydric alcohols include, e.g. ethylene glycol, ~,
propylene-1,2- and -1,3-glycol, butylene-1,4- and -2,3-glycol,
hexane-1,6-diol, octane-1,8-diol, neopentylglycol, cyclohexane
dimethanol (1,4-bis-hydroxymethylcyclohexane), 2-methyl-
propane-1,3-diol, glycerol, trimethylolpropane, hexane-1,2,6-
triol, butane,l,2,4-triol, trimethylolethane, pentaerythritol
quinitol, mannitol, and sorbitol, ethyl glycoside, diethylene-
glycol, triethyleneglycol, tetraethyleneglycol, polyethylene
glycols, dipropylene glycols, polypropylene glycols, di-
butylene glycol and polybutylene glycols. The polyesters may
LeA 15,476 -13-

1~84196 :
, :
also contain a proportion of carboxyl end groups. Polyesters
of lactones may also be used, e.g. f-caprolactone or hydroxy-
carboxylic acids, e.g. ~-hydroxycaproic acid.
The polyethers containing at least 2, generally 2
to 8 and preferably 2 or 3 hydroxyl groups which may also
be used according to the invention are known er se and may be
obtained, e.g. by the polymerization of epoxides, such as ;~
ethylene oxide, propylene oxide, butylene oxide, tetrahydro-
furan, styrene oxide or epichlorohydrin, each with itself,
e.g. in the presence of BF3, or by addition of these epoxides
optionally as mixtures or successively, to starting components
which contain reactive hydrogen atoms, such as alcohols or
amines, e.g. water, ethylene glycol, propylene-1,3- or -1,2-
glycol, trimethylolpropane, 4,4'-dihydroxydiphenylpropane,
aniline, ammonia, ethanolamine, or ethylene diamine. Sucrose
polyethers as described, e.g. in German Patent 1,064,938 and
British Patents 957,946 and 957,947 may also be used according
to the inventio~ Itis frequently preferred to use those poly-
ethers which contain predominantly primary OH groups (up to
90% by weight, based on all the OH groups present in the
polyether). Polyethers modified by vinyl polymers of the
type which may be obtained, e.g. by the polymerization of
styrene or acrylonitrile in the presence of polyethers (U.S.
Patent Specification Nos. 3,383,351; 3,304,273; 3,523,093 and
3,110,695 and German Patent Specification No. 1,152,536) and
polybutadienes which contain OH groups are also suitable.
Among the polythioethers there should be particularly
mentioned the condensation products of thiodiglycol with
itself and/or with other glycols, dicarboxylic acids, for-
maldehyde, aminocarboxylic acids or amino alcohols. The
products are polythio mixed ethers, polythioether esters or
LeA 15,476 -14-

108419~;
.~lythioether ester amides, depending on the cocomponent.
Suitable polyacetals are, e.g. the compounds which
may be obtained from glycols, such as diethylene glycol,
triethyleneglycol, 4,4'-dioxethoxy-diphenyldimethylmethane,
hexane-diol, and formaldehyde. Polyacetals suitable for the
purpose of the invention may also be prepared by the polymeriza-
tion of cyclic acetals.
Suitable polycarbonates with hydroxyl groups are
also known per se e.g., those which may be prepared ~y reacting
diols, such as propane-1,3-diol, butane-1,4-diol, and/or
hexane-1,6-diol, diethyleneglycol, triethylene glycol, or
tetraethyleneglycol, with diaryl carbonates, e.g. diphenyl-
carbonate or phosgene.
The polyester amides and polyamides include, e.g.
; 15 the predominantly linear condensates obtained from polyvalent
saturated and unsaturated carboxylic acids ~such as e.g~ phth~lic
acid or their anhydrides and polyvalent saturated and unsaturated
.. .. . ..
amino alcohol~ such as e.g. ethanol am me, diamines, polyamines
such as ethylene diamine, diethylene triamine and mixtures
thereof.
Suitable polyepoxides are, e.g. the known reaction
products of bisphenol A with epichlorohydrin.
Suita~le hydroxypolyacrylates include, e.g. the
known copolymers of olefines, such as acrylonitrile and/or
styrene with acrylic and/or methacrylic acid esters in which
the alcohol component consists at least partly of a diol,
such as ethylene glycol or propane-1,2-diol.
The preferred reactants used with the products
of the process for producing binders for powder lacquers
are, of course, solid representatives of the compounds given
above as examples, particularly those with softening points
between 60 and 120C and preferably between 80 and lOCC.
LeA 15,476 -15-

1`()84~96
The mixtures which are capable of cross-linking generally
contain from 0.5 to 1.5 hydroxyl groups per latent NCO groups,
based on the aforesaid polyhydroxyl compounds. The mixtures -
of reactants used as powder lacquers preferably have a
melting point of from 50 to 150C, preferably from 70 to 120C.
Care must be taken to ensure that the melting point of the
powder lacquer binder ready for use is at least 10 to 20C
below the cross-linking temperatures.
The mixtures of polyuretdione polyurethanes accord-
ing to the invention with the above-described compounds which
contain Zerewitinoff active hydrogen atoms may be prepared
in the same reaction vessel after the synthesis. Homogeneous,
clear, self-crosslinking two-component resins are thereby
obtained after evaporation of the solvent, e.g. in melt
extruders. The resins may be mixed with the known dyes,
pigments, fillers, other resins, hardening catalysts, auxiliary
agents, such as levelling agents, W absorbents, matting
agents, etc. in the conventional manner either at the same
time or in a separate operation. The binders may, of course,
be used unpigmented, e.g. as clear lacquers, or they may be
dissolved in solvents and used, e.g. for wire lacquering and
as electroinsulating materials.
; The advantages of the new polyuretdione polyaddition
products according to the invention are obvious:
1. Physiologically inert latent polyisocyanates
from which no compounds are split off are
obtained by a simple "in situ" process from
diisocyanates and alcohols without changing
the reaction vessel.
2. With suitable choice and combination of
LeA 15,476 -16-

1084196
starting compounds, the reactive systems
according to the invention may be prepared
not only in powder ~orm, as is preferred
according to the invention, i.e. in
crystalline form, but also in a resinous
or viscous form. ~
3. The simple method of preparing the new - polyuretdione polyurethanes as free
flowing, physiologically inert reactive
powders which are free from groups which -
are split off opens up new possibilities
in the production of powder lacquers which
; may be stored. The polyuretdione-poly-
urethane cross-linking agents are com-
patible with a variety of numerous hard,
linear or branched polyhydroxyl compounds
and may be mixed with them in extruders
without undergoing premature reactions. The
extruded resins obtained are hard and
brittle and may easily be ground down.
Powders applied to sheets by the hnown
electrostatic powder spray process flow at
temperatures of about 80 to 120C and may be
stoved at temperatures of from 130 to 220C,
preferably from 150 to 180C within 15 to
30 minutes. Matt to high gloss metal
coatings which are weather resistant and
elastic and have high impact strength
are obtained after stoving.
LeA 15,476 -17-

1084196 `
:
4. The reactive powders are stable in ~`~
storage and not blocking even under
extreme conditions (action of water,
; storage at 60C). They have no ten~
dency to spontaneous ignition or dust
explosions.
~ .
The invention will now be explained in more detail
with the aid of the following Examples. Unless otherwise
indicated, the parts given are parts by weight. The percentages ~ -
of latent NCO groups in the uxetdione refer to the NCO groups
actually available for a cross-linking reaction (OH end groups
o~ the cross-linking ~gent are taken into account).
Example 1
"In situ" process for the preparation of polyuret~ione poly-
urethanes
'~.
348 parts of tolylene-2,4-diisocyanate are dissolved
in 1300 parts of partly distilled toluene. 7.2 parts of
tri-n-butylphosphine are added to the mixture at 20C. The
dimerization product begins to separate after a reaction
time of only 5 minutes (gentle cooling is advisable at this
stage). By the end of one hour, the NCO value has dropped
from the original 48.3% to 34.0%. After 2.5 hours the NCO
value of the mixture is 31% (if the reaction temperature is
maintained at 20~C, the NCO value of the mixture thereafter
changesonl~insignificantly even after several hours!). When
the NCO content of the mixture has settled at 30 to 31~, the
dimerization catalyst is inactivated by stirring 2.28 parts of
sulphur into the mixture. The mixture is then heated to 90C
with stirring. A clear solution is obtained. 213 parts
of 2-ethyl-hexane-1,3-diol are then added to the diisocyanate
mixture and the reaction temperature is maintained at 90 to
LeA 15,476 -18-

108419~
~ ~.
110C for 6 hours. No more free NCO groups can then be
detected IR spectroscopically. The reaction mixture is left
to cool and the somewhat swelled crystal paste is spread out
on sheets and dried in air. A very fine, free flowing powder ~-
melting at from 146 to 168C is obtained. The average molecular -
weight of the polyuretdione polyurethane is 1889. The poly- `
uretdione polyurethane contains 11.8% of latent NCO groups. -
The method described in Example 1 is used to prepare
numerous other aromatic polyuretdione polyurethanes with
differing uretdione contents. The Table clearly shows the
influence of the interference diisocyanate on the melting point
of the polyuretdione polyurethanes.
'
,`'
.
.,.-~
~',
LeA 15,476 -19-

~Ei 4196
9L~ 51 ~aq
o
d~ ~ ~r u~ u~
S ~ ~1 U~ I` ~ ~
. .,
a ~ _, ~ CD ~
. ~
s~
~ .
O ~ o O O O U~ O
.p~ o _I _~ _I NO
. '~
-l ro~ U~ U~ U~ U~ U~ :
~rO l l l : .j
. J ~X 1 ,O
I ~J` _l,o~ I ~0 _l ol
l ~r~
~1 .q ~ ~:~
O ~_1 ~ I ~ I ~ I
'~ ~ x ,1 a)~ ~ ~ x ~'.
~ S ~ ~J _I ~ _I N ~1 P::
tq
U~ Irl ~D ~
~ol ~ ~ ~ 0~ ~D ~ ~D ~r ~ ~r ,
O ~ O N rt t~ _i tr~ O ~
.~ O
~ H ~ H . ~ O
a ~ a~ ~ c~
E~ ~ E~ ~ _l ~ _
a~ ~ a~
O ~1 ~ O a~ H ~H
_I .IJ ~ ~ ~1 ~ ~ ~ H E~ HE-i U~ H E~
~ o n~ ,a o ta 1~ c~ ~,, ~
O ~ ~ O ~ ~ ~ ~ ~ E~ O E~U I E~ O
u~ ~d ~ Id ~ ~1 ~ D ~
~rl U ~ S~ :~ r~ ~ h ~~) ~1 O~1 ` U ~1
.,,~ ~ a~ c~ ~1 0 Ql ~ ~1 a) ~1 a~ ~1 ~,~ a)
C~ h O 8 uo ~ o O tn h o ~ 8 dP ~1 8
~ ~ E3 ~ ~ ~1 Ei 1 ~ S:: o ~3 ~ :
,~ o ~ ,~ o r~ ~ o.,~ o ~ .,~ o
a ~ ~: ~ cl ~ ~; ~ a ~: a ~;-- a ~ `~
~z ~ ~ ~ u~ ~:
IjX3

1~84l96
Example 7
Polyuretdione polyurethane from dimeric hexamethylenediisocyanate
45 parts of butane-1,4-diol and 74 parts of _-
butanol are dissolved in 126 parts of toluene. About 20 parts
of toluene are distilled off to dry the alcohols. 0.5 ml of
benzoyl chloride and 0.5 ml of dibutyl tin dilaurate (20%
solution in ethyl glycol acetate) are added to the reaction
mixture. 384 parts of dimeric hexamethylenediisocyanate (2
NCO equivalent) dissolved in 20 parts of anhydrous toluene are
added dropwise to the mixture at room temperature in the course
of one hour. Gentle cooling is necessary. No more free NCO
groups can be detected by means of IR spectroscopy after a
reaction time of 3 hours. The polyuretdione polyurethane
crystallizes from the toluene solution. A somewhat waxy,
crystalline product melting at 75 to 83C is obtained after
drying in air. The polyuretdione polyurethane contains 10.6%
of latent NCO.
'''~
Exam~le 8
This example serves to demonstrate the possibility
of preparing highly concentrated lacquer solutions from
viscous polyuretdione polyurethanes.
A) 0.5 parts of benzoyl chloride and 1 part of
dibutyl tin dilaurate (20% solution in ethyl glycol acetate)
are added to 131.6 parts of 2-ethylhexane-1,3-diol, 6.2 parts ;~
of ethylene glycol and 152 parts of glycol monoethylether.
788 parts (4 NCO equivalents) of a polyisocyanate mixture
consisting substantially of dimeric hexamethylene diisocyanate
are added dropwise to this mixture at room temperature with
stirring (exclusion of moisture) in the course of 45 minutes.
The reaction mixture spontaneously heats up to 70-72C. It now
LeA 15,476 -21-

~108419~i
contains only 1.03% of free NCO groups. 269 parts of toluene
and 27 parts of glycol monoethylether are added and the mixture
is heated to 90C for one hour. No more free NCO groups can then
be detected by IR spectroscopy. The adjusted 80% solution in
toluene has a viscosity of 3840 cP at 20C and contains 8.15%
of latent NCO groups.
B) 100 parts (0.194 NCO equivalents) of the cross-
linking agent described under (A) are mixed with 25.85 parts of -
an 80% solution in toluene (0.097 OH equivalents) of a poly-
ester ~OH number 250-270) prepared from phthalic acid, hexa-
hydrophthalic acid and trimethylolpropane and 4.3 parts of tri-
methylolpropane (0.097 OH equivalents) dissolved in 1.07 parts
of toluene. The 80% lacquer solution has a viscosity of 6940 cP
at 20C.
C) When 100 parts (0.194 NCO equivalents) of the
polyuretdione polyurethane cross-linking agent described under -
(A) are mixed with 51.9 parts (0.194 OH equivalents) of an
80% solution in toluene of a polyester (OH number 250 to 270)
prepared from phthalic acid, hexahydrophthalic acid and tri-
methylolpropane, an 80% lacquer solution with a viscosity
of 16,200 cP at 20C is obtained.
The concentrated lacquer solutions may be diluted
to suitable viscosities with the conventional lacquer solvents.
Stoved lacquer films are hard and glossy with a good texture
and elastic and solvent-resistant (insoluble in toluene and
ethyl glycol acetate).
Examples 9-19
Polyuretdione polyurethanes synthesized from dimeric
tolylene diisocyanate and diols without an interference
LeA 15,476 22-

diisocyanate are summerized in the following Table (for
comparison with Examples 2-6).
General Method of Operatlon
1.5 parts of diol are dissolved in 1.5 liters of
toluene. Approximately 100 ml of toluene are then distilled
off. 1.2 mol of dimerized 2,4-diisocyanatotoluene are rapidly
introduced into this dehydrated reaction mixture at a reaction
temperature of 80 to 90C. The dimerized 2,4-diisocyanato-
toluene introduced first dissolves to form a clear solution
when stirred vigorously. The reaction mixture is then stirred `
for a further hour at 90C, during which time the poly- -~
uretdione polyurethane begins to precipitate from the toluene
solution. Only a small quantity of free NCO groups can by
that time be detected by IR spectroscopy. The reaction
mixture is then left to stand overnight at room temperature
without stirring. No more free NCO groups can be detected
by IR spectroscopy at the end of this time. The colorless,
slightly swollen crystal paste is then spread out on sheets
and dried in air. A dust fine, free-flowing polyuretdione
polyurethane powder is obtained (see Table 1). The IR
spectra of the polyuretdione polyurethanes show that charac- '
teristic intensive band of the uretdione group at 1780 cm 1.
LeA 15,476 -23-

184196 9L~ 'Sl ~1
O f ~1~ ~ O ~ I I N
g C ~ ( N~ l ~
1~ ~ ~ N ~ ~ N N N ~'1 N
Pl ~ N ~1 O O O O O O O O O O O
o ~ C
E D ~ ~ ~ ~ --l ~ ~ N ,1
~J ~ r ~
t~ H a H H H H H H H H
,~ I E ; L ¦ E E ~ D~ D~ U D ¦ U
OO ,~1 ~ ~ ~ U7~D 1~ 0 ~
X Z a~ ~ ~1 ~ ~ ~ _1 _1 ~1 ~1 ~1
~4 ` :.

1~84~96
Example 20
313.2 parts of tolylene-2,4-diisocyanate are
dissolved in 1300 parts of partly distilled toluene. 7.2
parts of tri-n- butyl-phosphine are added to the mixture at
from 5 to 7C. Dimerization product begins to separate after
a short time. After 1.5 hours, the NCO value (free NCO) has
dropped from an initial 48.3% to 29.6%. After 3.5 hours the
NCO value (free NCO) is 26.6%. The dimerization catalyst is
then inactivated by stirring in 22.8 parts of a hot 10% solution
of sulphur in toluene, and 33.6 parts of hexamethylene diiso-
cyanate are added to the reaction mixture. The NCO content
of the mixture is then 28.7~. The mixture is heated to 90C
with stirring, a clear solution being obtained. Even this
temperature treatment no longer changes the NCO content (free
NCO) although uretdione diisocyanate and free diisocyanate are
present side-by-side in the reaction mixture. 194.5 parts
of 2-ethylhexane-1,3-diol are then poured all at once into
the reaction mixture. The mixture is then stirred at 90C for
3 hours. No more free NCO can then be detected by IR
spectroscopy. The mixture is left to cool. Polyuretdione
; polyurethanes crystallizes from the toluene solution. The
crystal paste is spread out on sheets and dried in air. A
very fine, free-flowing powder melting at 160 to 163C is
obtained. The average molecular weight of the polyuretdione
polyurethane is 3650. The polyuretdione polyurethane contains
10.3% of latent NCO (the OH end groups have already been
deducted from the total uretdione content of the polyuretdione
polyurethane, as in all the other Examples).
Exa_ple 21
313.2 parts of tolylene-2,4-diisocyanate are dis-
solved in 975 parts of anhydrous methyl glycol acetate and
LeA 15,476 -25-

1084196
325 parts of anhydrous toluene. The reaction mixture is cooled
to 10C and 7.2 parts of tri-n-butylphosphine are added.
The reaction mixture is stirred for 3.5 hours at 10 to 15C
with cooling. 22.8 parts of a 10% solution of sulphur in
toluene are then added. A clear solution is obtained after
heating the reaction mixture to 100C. 33.6 parts of hexa-
methylenediisocyanate are added to this solution. The NCO
content of the mixture (free NCO) is then 26.8%. 0.3 parts of
benzoyl chloride and 182 parts of 2-ethyl-hexane-1,3-diol -
are then added and the mixture is stirred under nitrogen at -
100C for 4 hours. Only a little free NCO can then be
detected by IR spectroscopy. After the addition of 0.4 parts
of dibutyl tin dilaurate (20% solution in ethyl glycol acetate)
the mixture is stirred for one more hour. No more free NCO
can then be detected spectroscopically in the reaction mixture.
The IR spectrum shows only the characteristic uretdione band
at 1780 cm 1. The polyuretdione polyurethane crystallizes
from the solvent mixture on cooling. A fine crystalline
powder melting at from 140 to 155C is obtained af~er drying.
The average molecular weight is 3826. The polyuretdione poly-
urethane contains 11.35% of latent NCO.
Example 22
Pre~aration of a powder lacquer ready for use
1. Method of operation:
~he required components (100 parts of a branched
terephthalate polyester (1.5~ OH~ and 34 parts of polyuretdione
polyurethane f~om Example 21) are mixed with finely divided ti-
tanium dioxide pigment. A commercial copolymer of butyl acrylate
and 2-ethylhexylacrylate of an approx.viscosity of 200 000 cP!
20C is used as levelling agent. It is incorporated in the form
of a so-called master batch, i.e. 100 parts of polyester are
melted with 10 parts of
Le ~ 15,476 - 26 -

1~8419t~
levelling agent and the mixture is size reduced when solidified.
The mixture is homogenized in a commercial two-
shaft self cleaning extruder. The jacket temperature is
adjusted so that the temperature of the outlet of the apparatus
is about 125C. The molten cake may either be left to itself,
or as is customary in practice, it may be rapidly cooled in
a continuously operating squeezing and cooling apparatus. When
it has been cooled to temperatures of from 20 to 30C, it is
first ground coarsely and then fineground while cooled with
blowers. The finely divided powder obtained is then freed
; from coarser particles larger than about 90 ~m by wind or
mechanical sifting.
The powder lacquer obtained in this way is then
applied by means of an electrostatic spray device. Con- -~ ;
ventional commercial products may be used for this purpose.
.
The voltage used may be either positive or negative
in relation to the workpiece and may be about 20 to 100 KV.
To obtain homogeneous, smoothly flowing and -
mechanically perfect films, the powder is then melted and
hardened in a stoving oven at temperatures of from 16D to
220C.
2. The usual lacquer technical properties of a
combination of terephthalate polyester/polyuretdione poly-
urethane cross-linking agent from Example 21: Steel sheets
Of thickness 0.5 mm are used unless
otherwise indicated.
The tests are carried out after the samples have
been stoved at 180C for 30 minutes or 200C for 10 minutes.
T.AZI 1 I; A 7~ ~~

1084196
Elasticitv_tests:
1. Elasticity test by Erichsen cupping according
to DIN 53 156: 9 mm or until the metal sheet cracks.
2. Conical mandrel according to ASTM D 522-
41: 37~ (= free from faults).
3. Grid cut according to DIN 53 151 apparatusGt. C: O (= free from faults, optimal).
4. Pencil hardness according to DIN 46 450*: 3H
* Regulations for testing wire lacquers.
The knife test produces a tough elastic chip and
confirms the excellent adherence in the grid cut test.
The solvent resistance indicates good chemical
cross-linking. The lacquers are resistant to toluene, ethyl
glycol acetate and acetone and may be exposed to them for
several minutes before the surface begins to soften. The
coating does not dissolve but only swells slightly.
The corrosion resistance i5 tested by the salt
spray test according to DIN 53 167. The surface to which
the coating is applied is pretreated with zinc phosphate
(similar to that sold under the Trademarks "Bonder 125", of
Metallgesellschaft, or "Granodine A 16", of Collardin). --
The corrosion resistance test shows undersurface rusting of at
the most 3 mm of a previously applied cut after 400 hours. The
adherence test by the grid cut or by adhesive tape carried out ~ -
immediately after removal from the salt spray gives the best
possible results.
The test for resistance to washing liquor carried
out to determine the performance in conventional household
detergents, again using steel sheet pretreated with zinc
phosphate, shows a resistance without faults after more than
LeA 15,476 -28-

1084196 ~
40 hours' exposure to the test solution at 100C.
Very smooth lacquer surfaces without orange peel
effect or retraction from the edges is observed in all cases.
The films are homogeneous and free from bubbles.
~
Example 23
395 parts of a polyisocyanate mixture obtained by
dimerizing hexamethylenediisocyanate are dissolved in 200
parts of acetone. 0.45 parts of benzyl dimethylamine and 9
parts of water are added to the mixture and the reaction ~
mixture is then heated to 60C for 2 hours. 11~2 parts of ~-
carbon dioxide are evolved. 200 parts of n-butanol are then
added to the mixture which is then heated to 90C for a
further 3 hours. The acetone is distilled off and the resulting
melt is poured out on metal sheets. The polyuretdione poly-
urea obtained has a melting point of 70 to 77C, an average
molecular weight of 922 and a latent NCO content of 12.15%.
The IR spectrum of the polyuretdione polyurea has the --~
characteristic uretdione band at 1760 to 1780 cm 1.
Example 24
,.
348 parts of dimerized tolylene diisocyanate are
dissolved in 975 parts of methyl glycol acetate and 325 parts
of toluene at 100C. 41.4 parts of n-butanol are added to
the mixture which is then heated to 110C for 30 minutes.
15.1 parts of water and 0.10 parts of benzyl dimethylamine
are then added at 110C. 18.6 liters of carbon dioxide are
evolved in the course of 4.5 hours while the temperature is
kept constant. The polyuretdione polyurea obtained crystallizes
from the reaction solution on cooling. After drying, a free-
flowing powder melting at from 215 to 219C is obtained. The
LeA 15,476 -29-

10~4:196 ~ ~
polyuretdione polyurea has an average molecular weight of ~ ~
1314 and contains 18.3% of latent NCO. ~:
. .
`
LeA 15,476 ~30-